If you want to get ahead, get a thinktank. These vessels of thought have in the past few years seemed to proliferate right, left and centre. One reader has some concerns about their influence in the pages of the Guardian. He writes: "When reading many articles or reports, a 'thinktank' is often quoted as having made a pronouncement which is used as an argument in favour of, or against, the matter being reported. But all these 'thinktanks' are not the same, many being fronts for very prejudiced organisations or groups. Is it possible to reveal the backers of these 'tanks', who pays for them and what their slant is? Is there any organisation that could assess them, or create a 'best buy' or ranking on the basis of their independence? When referring to films, for example, you use a range of one to five stars to indicate their quality. Would you put yourself at risk of a court case if you did the same on the independence of a 'tank'? We could do with a Guardian booklet on this!"

It's an interesting idea. The views of thinktanks are a staple part of the broadsheet diet. A search on the Guardian's website shows that there are 840 stories that have been given a "thinktanks" tag, because they are either based on the findings of a thinktank or use their research to form a crucial part of the story. This is particularly true in politics. For instance, in an article on 13 March 2012 David Laws, one of Nick Clegg's closest advisers, warned "that the coalition faces paralysis if the Conservatives and Liberal Democrats go too far in seeking to differentiate themselves from one another by repeatedly blocking proposals". He did so at a meeting organised by Brightblue, a centrist thinktank.

I asked two seasoned senior journalists what they thought of the idea. Patrick Butler, social policy editor, said: "Specialist journalists are all very aware of where these thinktanks are politically. In terms of the government of the day, the Institute for Public Policy Research (IPPR) was always thought to be Tony Blair's favourite thinktank and Policy Exchange was seen as being a way of working out what the Cameronians were thinking. Among the policy wonks some people think thinktanks should be completely transparent about where their funding comes from. Some are and some aren't."

Are they influential? Butler said: "IPPR was always seen as close to government in Tony Blair's time and it was thought their thinking was behind child poverty policy and the baby bond. But two of the right-of-centre thinktanks felt left out of the conversation by Andrew Lansley when he was drawing up the health bill. Besides a small team of officials, it's all his own work."

Michael White, an assistant editor and former political editor, said: "The reader has a point, of course he does. Some thinktanks are rooted in serious quasi-academic study and enjoy a high reputation. The Institute for Fiscal Studies is perhaps the most obvious current example, though Chatham House – the Royal Institute of International Affairs – has been so for nearly 100 years. Even they are criticised for perceived institutional or cultural bias. But then so are university departments.

"By way of contrast, the Taxpayers' Alliance, which is a lobbying or pressure group rather than a tank, but is widely quoted by low-tax tabloids, is there to promote anti-tax views, just as pro- and anti-EU groups have their own known agendas. It does not mean they do not sometimes publish good work.

"The Guardian tries to quote reputable ones … They [thinktanks] gain and lose fashion, sometimes get a second wind in opposition or under a smart new director. Thus the RSA is regaining profile as a forum for ideas under the clever ex-Blair adviser Matthew Taylor, who is very party-political but pretty straight.

"Star ratings? It's a thought but could be risky. The old adage holds: let the buyer beware."